The present invention relates to grinders, and more particularly to such a grinder which comprises a power drive unit, and three interchangeable grinding units, wherein the first grinding unit is adapted for turning a grinding bit in X-axis direction; the second grinding unit is adapted for turning a grinding bit in Y-axis direction; the third grinding unit is adapted for reciprocating a grinding bit.
A variety of grinders have been disclosed for different grinding purposes, and have appeared on the market. Because different grinders are designed for different grinding purposes, one shall have to prepare many grinders for use in different conditions. It is expensive to prepare a set of grinders. Furthermore, it is inconvenient to carry a set of grinders. When not in use, much storage space is needed to store the grinders.